1. Field of the Invention
The present invention relates to a routing method for determining a destination in a computer network having multiple interconnected nodes, and more particularly, to a method for measuring packet delays among remotely located gateways and processing routing in application layers of the gateways using the packet delays.
2. Description of the Related Art
In general, factors affecting the quality of service (QoS) of the Internet are packet delay, packet loss, jitter and the like. In a phone-to-phone Internet telephony system, a gateway of a calling party transfers a voice call to a gateway of a called party. In transferring the voice call, the best way for ensuring the generally accepted quality is to utilize packet traffic flow control among routers. However, in consideration of characteristics of the Internet, guaranteed QoS cannot be offered by the Internet Protocol (IP) service.
As is known well, a computer network includes connection of various nodes, each having a layered protocol structure, for example, a model known as the Open Systems Internconnect (OSI) Seven-layer model. The Internet, which is the most widely being used as the computer network, includes a plurality of routers.
These routers perform routing functions according to various algorithms such as a Shortest Path First (SPF) algorithm, a Shortest Available Path First (SAPF) algorithm, a Widest Available Path First (WAPF) algorithm, a Dynamic Random Routing (DRR) algorithm and so on.
Here, the SPF algorithm is used to transfer a voice call between IP end terminals along the shortest path. However, a problem with the SPF algorithm is that a call may be blocked when the capability of the shortest path is insufficient. To overcome this problem, the SAPF or WAPF algorithm employs alternative paths in the case where the shortest path is blocked. The DRR algorithm employs both a direct path and an alternative path. That is to say, if there is a new incoming voice call, a direct path is tried first and then an alternative path is used when the direct path is not available.
However, these known routing algorithms are simply based on the number of hops or possible bands, leaving characteristics of packets for real-time traffic in an IP network out of consideration. Thus, in such Internet telephony systems requiring real-time services, QoS guarantees cannot be rendered. Also, remotely located routers constituting the Internet are owned and managed by different operators. Thus, even if an improved algorithm for real-time traffic is developed, it cannot be suited to all routers from the viewpoints of specific interest parties, for example, Internet phone service providers.